tuples, variable binding specifications, wildcards (`..`), and placeholders
(`_`). A `match` expression has a *head expression*, which is the value to
compare to the patterns. The type of the patterns must equal the type of the
tuples, variable binding specifications, wildcards (`..`), and placeholders
(`_`). A `match` expression has a *head expression*, which is the value to
compare to the patterns. The type of the patterns must equal the type of the